Construction vehicles, such as a motor grader, are usually operated at uneven sites, and are provided with an operator compartment protecting device in order to protect the operator in the event of falling objects or the vehicle is overturned.
For example, an operator compartment protecting device 4, including a support pole 2 and a ceiling 3, as shown in FIG. 1, is mounted on a vehicle body 1 in order to prevent breakage of an operator compartment 5 which could occur if the vehicle is overturned or hit by a falling object, and such device thereby protects the operator. In such an operator compartment protecting device 4, the support pole 2 is permanently fixed to the ceiling 3 by welding, and the lower portion of the support pole 2 is firmly mounted on the vehicle body 1 by means of bolts. The ceiling 3 protrudes over the operator compartment 5. Thus, when the hydraulic units or the like mounted on the vehicle body 1 below the operator compartment 5 are to be inspected or repaired, the operator compartment 5 cannot be lifted out of the way because of the presence of the operator compartment protecting device 4. The operator compartment protecting device 4 must first be unbolted and moved aside, and then the operator compartment 5 can be lifted up and moved out of the way.
However, the work of removing the operator compartment protecting device 4 is very troublesome and expensive, because the support pole 2 is firmly mounted on the vehicle body 1 by means of the bolts, and loosening of the bolts is difficult, and further because the operator compartment protecting device 4 is very heavy and thus requires lifting gear, such as a crane or a wrecker truck, to remove it. Accordingly, the inspection or repair of the portion of the vehicle body 1 located below the operator compartment 5 is very troublesome and expensive.